Relativistic hydrodynamics, viewed as an effective field theory, is formulated in a derivative expansion. Studies of applicability of relativistic hydrodynamics in nuclear collisions at RHIC and LHC prompted 1302.0697 to explore convergence properties of this expansion. This and subsequent works showed that the Bjorken flow gives rise to a gradient expansion with a vanishing radius of convergence in all but a single studied quark-gluon plasma model. In my talk I will overview the current status of this field, as well as outline new developments on this topic that, for the first time, allow to make definite statements about the
convergence of hydrodynamic gradient expansion. New results follow from 2007.05524 and an ongoing work.